It is known that masonry structures, constructed of concrete, brick, concrete block and the like can have prolonged lives if the substrate structure is coated with a protective sealer and/or coating. All such structures are high in silicon dioxide content, and are subject to varying degrees of environmental decay, erosion, and/or corrosion.
It has been found in the past that certain alkylalkoxysilanes can function as effective waterproofing aids, and decay, erosion and corrosion inhibitors for masonry structures containing silicon dioxide, but compositions which have been heretofore developed for taking advantage of this property of alkyl alkoxysilanes have not been very efficient. For example, U.S. Pat. No. 3,772,065, discloses an alcohol solvent system for alkyltrialkoxysilanes and for their lower oligomers as water repellant impregnants for masonry. However, it has been found in testing that alcohol solvents are substantially ineffective in securing efficient waterproofing performance from such silane impregnants.
Among the disadvantages of an alcohol solvent system are flammability, and very low flash points, and high vapor pressure, allowing the alcohol solvent system to rapidly evaporate, even at ambient conditions. Rapid evaporation means poor and ineffective penetration of the alkylalkoxysilane into the masonry structure. As a result, the water repellancy and corrosion inhibition is not nearly as great, as it otherwise might be; and one must use much higher concentration levels of silane in such impregnants, making the products more expensive.
Accordingly, it is a principal object of the present invention to develop a composition for waterproofing and inhibiting corrosion of silicon dioxide containing substrates such as masonry structures, concrete structures, brick structures and the like, which employs certain highly effective alkylalkoxysilanes in combination with a certain select group of aromatic and aliphatic and oxygenated hydrocarbon solvents, with the solvent being free of alcohol groups. Surprisingly, when this combination is employed, the solvent functions as a highly effective carrier for the alkylalkoxysilane. The solvent itself has a vapor pressure such that it gradually evaporates at ambient conditions. This gradual evaporation allows the penetration of the alkylalkoxysilane into the pores of the masonry structure. As a result, the hydrophobic moiety of the alkylalkoxysilane is deeply impermeated into the masonry structure, with the silane portion of the moiety bonded to silicon dioxide of the masonry substrate.
It is important that no alcohol solvent be present. Alcohol solvent has been found to be undesirable because of its flammability, low flash point, and also in that it at times has a tendency to inhibit the bonding of the silane to the silicon dioxide of the substrate.
It is, of course, a primary objective of the invention to provide the composition mentioned above which is a highly effective waterproofing, decay, erosion and corrosion inhibiting composition for masonry substrates.
It is another objective of the present invention to provide the above composition which allows the alkylalkoxysilane to effectively penetrate the pores of the masonry structure and effectively lock itself to the structure through reaction of the silane moiety with the silicon dioxide of the masonry structure.
It is a further object of the invention to provide specific solvents which enhance significantly the water repellant characteristics of the alkylalkoxysilanes when applied to masonry compositions.
An even further object of the present invention is to provide a composition and method which synergistically act together to cooperatively carry the alkylalkoxysilane impregnate to the masonry structure, and to effectively bond the same to the masonry structure, once penetration is accomplished.
The method and manner of accomplishing each of the above objectives will become apparent from the detailed description of the invention which will follow hereinafter.